The little choices airlines make designing their seats can make a huge difference in your journey

Do you ache all over after flying in a coach seat? That could be by design.

Airlines have lots of choices when they order seats for their airplanes. Those selections go a long way to determining how comfortable—or uncomfortable—their customers will be.

The seat bottom is one of the most crucial elements in seat comfort, and one of the most carefully studied. Longer is better: You get more support under your thighs. But some airlines scrimp.

Some reduce seat length to save weight. “You get hot spots on the back of your thighs. You’re in misery but you don’t know why,” says Robert Funk, vice president for sales and marketing for the seating division of Zodiac Aerospace.

On the Edge of Your Seat

Here are some of the key specs airlines must consider:

Reclining the seat really does make seats more comfortable. Pressure gets distributed on your back.

Longer seat length reduces stress on the back of your thighs.

Seat pan padding and design determines how weight is distributed and how much pressure is on the bottom of your pelvis. More pressure, more discomfort.

The angle of the seat back meeting the seat pan affects comfort. Closer to 90 degrees is less comfortable.

Height off the floor is an issue. Asian airlines often order shorter seats. European airlines sometimes order taller seats.

Leg and calf rests help distribute weight and make seats more comfortable.

Reclining the seat really does make seats more comfortable. Pressure gets distributed on your back.

Longer seat length reduces stress on the back of your thighs.

Seat pan padding and design determines how weight is distributed and how much pressure is on the bottom of your pelvis. More pressure, more discomfort.

The angle of the seat back meeting the seat pan affects comfort. Closer to 90 degrees is less comfortable.

Height off the floor is an issue. Asian airlines often order shorter seats. European airlines sometimes order taller seats.

Leg and calf rests help distribute weight and make seats more comfortable.

Longer seat length reduces stress on the back of your thighs.

Reclining the seat really does make seats more comfortable. Pressure gets distributed on your back.

Seat pan padding and design determines how weight is distributed and how much pressure is on the bottom of your pelvis. More pressure, more discomfort.

The angle of the seat back meeting the seat pan affects comfort. Closer to 90 degrees is less comfortable.

Height off the floor is an issue. Asian airlines often order shorter seats. European airlines sometimes order taller seats.

Leg and calf rests help distribute weight and make seats more comfortable.

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1. Reclining the seat really does make seats more comfortable. Pressure gets distributed on your back.

2. The angle of the seat back meeting the seat pan affects comfort. Closer to 90 degrees is less comfortable.

3. Longer seat length reduces stress on the back of your thighs.

4. Seat pan padding and design determines how weight is distributed and how much pressure is on the bottom of your pelvis. More pressure, more discomfort.

5. Height off the floor is an issue. Asian airlines often order shorter seats. European airlines sometimes order taller seats.

6. Leg and calf rests help distribute weight and make seats more comfortable.

Sources: Rockwell Collins; Zodiac Aerospace

Most U.S. airlines go with an average length on the seat bottom, about 18 inches.
Singapore Airlines
designed a Zodiac seat for its premium economy cabins on long-range Airbus A350s that has a 19-inch seat bottom. Those seats also have leg rests, which can take strain off muscles and increase blood flow, and recline with the seat sliding up as well as forward, so you don’t slide out of it when you lean back during 18-hour flights.

Another airline choice that affects your comfort: how high the seat is off the floor. About 18 inches is standard, but some European airlines with generally tall clientele want seats constructed higher, so long legs rest more naturally. Some Asian airlines order seats at 17 inches cushion height.

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Southwest Airlines
happens to have a variety of heights—some planes with seats 18.2 inches off the floor and others with just 17.2 inches. (At 6-foot-1, I can feel the difference.) The lower seat, found on Southwest’s new 737-8 MAX airplanes, “is designed to help increase the personal space for our customers,” a spokesman says.

Seat makers say many factors influence seat comfort far beyond their control. The length of the flight affects how comfortable passengers think a seat is. So do cabin temperature and lighting. The temperament of passengers when they get on the plane also affects comfort assessments—if you’re frazzled from the hassles and frustrated by TSA, you’re more likely to think the seat is uncomfortable. Friendliness of flight attendants can help or hurt seat-comfort surveys, too.

Airlines have their long-held prejudices on seats. Some prefer a firm cushion. Others want softer. Even when manufacturers suggest one particular firmness that they think provides ideal support and comfort for most passengers, some airlines insist on modifications, says Alex Pozzi, vice president of technology and seating development at
Rockwell Collins’s
seat-manufacturing division. That’s based on assumptions that “our particular market wants X,” he says. (Mr. Pozzi won’t name names.)

“There’s some science there, and some not-so-much science,” he says.

The cleanliness of the airplane is a big factor in seating comfort scores. In addition, studies show more attractive color combinations score higher. “A seat that looked less attractive always rated less comfortable,” even when it was the exact same seat, Mr. Pozzi says.

Bad news for travelers who think no one should recline into their space: Reclining actually improves comfort. Some of your weight gets shifted to the seat back from the seat bottom. Distributing weight across more seat surface is better for blood flow and pressure on key body parts.

Airlines can adjust how far their seats can recline, anywhere from 0 to 6 inches. As rows get smaller and airlines pack in more seats, airlines need to give more thought to reclining allowance than they sometimes do, Mr. Pozzi says. Some think they’re doing customers a favor by giving them lots of recline.

Manufacturers say they can achieve greater comfort when the support materials and padding distribute weight so that as little as possible falls on a pair of bones on the bottom of the pelvis known as the sit bones. You can feel them when you’re sitting on something hard, says Andy Severance, director of strategic marketing for premium cabins at Zodiac.

Most seat bottoms for aircraft are no longer made with hard metal seat pans topped with thick padding. Instead, the bottom structure is a flexible diaphragm that adjusts to different shapes and sizes and moves with people as they squirm in a seat, topped with minimal foam padding.

Fred Hughes, left, and Sebastiaan Does of Zodiac Aerospace examine a completed premium economy seat. The seat was specially designed for ultralong flights, some stretching to 18 or 19 hours. The seat bottom angles up as the back reclines to allow easier sleeping.
Photo:
Scott McCartney/The Wall Street Journal

To test designs, manufacturers typically recruit lots of volunteers to sit in seats for hours, recording both data and comments on how uncomfortable they are. Zodiac recruits testers from a local college near its Gainesville, Texas, manufacturing plant, paying them $10 to $12 an hour plus lunch.

Zodiac offers a two-hour seat, a two-to-six hour seat and a seat for flights eight hours or longer.

One issue for manufacturers is that airplanes these days get used for longer and longer flights. Regional jets designed for short hops of only a couple of hours now sometimes fly four-hour trips. Planes designed initially for short trips like the Boeing 737 now fly cross-country.

Airlines get all kinds of options on aircraft seats. Foot and calf rests are options rarely used by U.S. airlines but more common overseas. A one-piece food tray is more robust than a bi-fold. Coach seats can have reading lights, USB ports, 13.3-inch monitors, dual water bottle holders and under-seat boxes for entertainment gear so there’s no box on the floor blocking under-seat storage and foot space.

Many airlines, of course, choose not to provide those conveniences.

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